Add support for GL_EXT_multisampled_render_to_texture.

src/gpu/gl/GrGLCaps.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrGLCaps_DEFINED
 #define GrGLCaps_DEFINED
@@ skipping 38 matching lines @@
      * semantics of how / when a resolve is performed.
      */
     enum MSFBOType {
         /**
          * no support for MSAA FBOs
          */
         kNone_MSFBOType = 0,
         /**
          * GL3.0-style MSAA FBO (GL_ARB_framebuffer_object)
          */
-        kDesktopARB_MSFBOType,
+        kDesktop_ARB_MSFBOType,
         /**
          * earlier GL_EXT_framebuffer* extensions
          */
-        kDesktopEXT_MSFBOType,
+        kDesktop_EXT_MSFBOType,
         /**
          * GL_APPLE_framebuffer_multisample ES extension
          */
-        kAppleES_MSFBOType,
+        kES_Apple_MSFBOType,
         /**
-         * GL_IMG_multisampled_render_to_texture
+         * GL_IMG_multisampled_render_to_texture. This variation does not have MSAA renderbuffers.
+         * Instead the texture is multisampled when bound to the FBO and then resolved automatically
+         * when read. It also defines an alternate value for GL_MAX_SAMPLES (which we call
+         * GR_GL_MAX_SAMPLES_IMG).
          */
-        kImaginationES_MSFBOType,
+        kES_IMG_MsToTexture_MSFBOType,
+        /**
+         * GL_EXT_multisampled_render_to_texture. Same as the IMG one above but uses the standard
+         * GL_MAX_SAMPLES value.
+         */
+        kES_EXT_MsToTexture_MSFBOType,
     };
 
     enum CoverageAAType {
         /**
          * No coverage sample support
          */
         kNone_CoverageAAType,
 
         /**
          * GL_NV_framebuffer_multisample_coverage
@@ skipping 56 matching lines @@
     bool isColorConfigAndStencilFormatVerified(
                     GrPixelConfig config,
                     const GrGLStencilBuffer::Format& format) const;
 
     /**
      * Reports the type of MSAA FBO support.
      */
     MSFBOType msFBOType() const { return fMSFBOType; }
 
     /**
+     * Does the supported MSAA FBO extension have MSAA renderbuffers?
+     */
+    bool usesMSAARenderBuffers() const {
+        return kNone_MSFBOType != fMSFBOType &&
+               kES_IMG_MsToTexture_MSFBOType != fMSFBOType &&
+               kES_EXT_MsToTexture_MSFBOType != fMSFBOType;
+    }
+
+    /**
+     * Is the MSAA FBO extension one where the texture is multisampled when bound to an FBO and
+     * then implicitly resolved when read.
+     */
+    bool usesImplicitMSAAResolve() const {
+        return kES_IMG_MsToTexture_MSFBOType == fMSFBOType ||
+               kES_EXT_MsToTexture_MSFBOType == fMSFBOType;
+    }
+
+    /**
      * Reports the type of coverage sample AA support.
      */
     CoverageAAType coverageAAType() const { return fCoverageAAType; }
 
     /**
      * Chooses a supported coverage mode based on a desired sample count. The
      * desired sample count is rounded up the next supported coverage sample
      * count unless a it is larger than the max in which case it is rounded
      * down. Once a coverage sample count is decided, the supported mode with
      * the fewest color samples is chosen.
@@ skipping 155 matching lines @@
     bool fFragCoordsConventionSupport : 1;
     bool fVertexArrayObjectSupport : 1;
     bool fUseNonVBOVertexAndIndexDynamicData : 1;
     bool fIsCoreProfile : 1;
     bool fDiscardFBSupport : 1;
 
     typedef GrDrawTargetCaps INHERITED;
 };
 
 #endif